Projectile fuze with unitary deformable detent

ABSTRACT

The arming member of a projectile fuze is held against a spring in its unarmed position prior to launch by a unitary deformable detent member in the form of a tube that has been flattened and bent at one end. The gas pressure during launch causes the bent end to open up and unbend to release the arming member, thus permitting the latter to move to its armed position.

United States Patent Zagharin July 15, 1975 [54] PROJECTILE FUZE WITH UNITARY 2.918.870 l2/l959 Meister lO2/49.6 3.000.315 9/l96l Anastasia et a]... l()2/70.2 R DEFORMABLE DETENT 3.343.489 9/!967 Whitehouse 102/496 (75] Inventor: Alexey T. Z charin, r ipp nyv 3.362.333 l/l968 Czajkowski et al 102/81 [73] Assignee: The United States of America as glammerslamucl Engle represented by the Secretary of the Allorm). Agem, 0r Firm-Nathan Edelberg; Robert P. Army, Washington DC Gibson; Thomas R. Webb [22] Filed: Apr. 6, 1973 [57] ABSTRACT [2]] Appl- N05 348316 The arming member ofa projectile fuze is held against a spring in its unarmed position prior to launch by a [52] s H |02/70 2 102/81; 102/496 unitary deformable detent member in the form of a [5 1] Int CL H 2 15/40 tube that has been flattened and bent at one end. The [58] Fidd f Search H 102/702' 49.6 9 3] gas pressure during launch causes the bent end to open up and unbend to release the arming member, [56] References Cited thus permitting the latter to move to its armed posi- UNITED STATES PATENTS 2.887.056 5/1959 Ferret 102/702 R 8 Claims, 8 Drawing Figures PROJECTILE FUZE WITH UNITARY DEFORMABLE DETENT BACKGROUND OF THE INVENTION Projectile fuzes usually include one or more safing mechanisms to keep the component of the firing train containing the sensitive element, e.g., detonator, outof-line from the main explosive charge prior to launching of the projectile.

Forces incident to the launch environment are utilized to operate the safing mechanisms, such forces being axial inertia or set-back, centrifugal force due to projectile spin, propellant gas pressures, etc. Selection of the desired environmental force is based on the greatest signal-to-noise ratio. Signal being the actual force derived from the launch environment, and noise being the force derived through handling. One of the largest ratios is achieved by the use of the propellant gas pressures. In this case, since mechanical means are required to restrain the sensitive element out-of-Iine, the pressure sensing safing mechanism must provide mechanical displacement or movement to release the sensitive element and permit alignment of the explosive or firing train.

The use of a pressure signal to provide safing has been considered for decades, and various means have been proposed and used. One of the few successful methods to date has been the use of an axially slidable pressure piston which, when acted upon, would move a separate detent member the required distance to release the sensitive element. However, the pressure piston requires a dynamic seal, which is a critical element. In case of failure, the hot gases will penetrate the fuze and possibly ignite the firing train. Also, the pressure piston usually has to move forwardly, in opposition to the set-back force. The use of such pistons usually requires additional mechanical linkages or parts, with attendant reduction of reliability and increase in quality control during manufacture. Furthermore, the detent member requires some type of lockout to retain it in the armed condition once actuated, thus adding to the number of parts required.

The bellows type of pressure-mechanical transducer has also been proposed and use. However, like a piston, a bellows also provides primarily axial motion, and is susceptible to gas leakage. A bellows requires a high degree of quality control to assure a hermetic seal, and is rupture prone. The cost per unit is relatively high. It is not particularly applicable to high pressure usage, and requires additional hardware for lock-out.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fuze, for an explosive projectile, having a new and improved gas pressure-actuated safing and arming mechanism.

Another object is to provide a gas pressure-actuated safing and arming mechanism requiring only a single (unitary) deformable detent member for responding to the gas pressure and releasing the arming member.

In accordance with the invention, an arming member, or other element of the firing train, of a projectile fuze is held against a biasing means in its unarmed or inoperative position prior to launch by an elongated unitary deformable detent member. During launch, the gas pressure causes the deformable detent member to bend away from the firing member, permitting the latter to move to its armed position. The detent member preferably comprises an elongated deformable tubular member, having an open end fixed in the fuze and exposed to the propellant and a closed end which has been flattened and bent away from the axis of the open end, and a rigid detent member having one end attached to or integral with the bent end of the tubular member and the other end engaged with a detent shoulder on the firing member.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an axial section view of a round of ammunition having a fuze incorporating the present invention positioned within a launch tube or barrel.

FIG. 2 is an axial section view of the fuze of FIG. 1.

FIG. 3 is an axial section view taken on line 33 of FIG. 2.

FIG. 4 is an end elevation view of FIG. 3 in the direction of the arrows 44.

FIG. 5 is a transverse section view taken on line 5-5 of FIG. 3.

FIG. 6 is a schematic circuit diagram of the firing train.

FIG. 7 is a side elevation view of a modified detent member.

FIG. 8 is an axial section view taken along line 88 of FIG. 7.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Referring to FIG. 1, an explosive projectile l and separate propellant 3 are positioned in axially spaced relation in a launch tube or barrel 5. The tube 5 and projectile I may be provided with conventional rifling grooves and rotating bands (not shown) to impart stabilizing spin to the projectile during launch.

Projectile 1 comprises a hollow cylindrical metal body 7 closed at its front end by a deformable metal nose cone 9 and at its rear end by a fuze II which embodies the present invention. The fuze 11 comprises a main body portion 13, mounted in a large recess 15 in projectile l, and a reduced extension 17 mounted in a smaller recess 19 in the projectile. The rear interior of the projectile is filled with a shaped charge 21, e.g., of octal, bounded by a conical metal liner 23. A second metal cone 25 is mounted in spaced relation within the nose cone 9 by insulation 27. Two insulated wires 29 and 31 connect the two nose cones to two of four terminals 32 (see FIGS. 3, 4 and 8) in the fuze 11. The nose cones 9 and 25 collapse on impact with a target and contact each other to close a firing circuit in the fuze. Two other insulated wires 33 and 35 connect the other two terminals 32 to a battery or other voltage source (see FIG. 6) external to the launch tube 5.

The details of fuze 11 are shown in FIGS. 2 through 5. The fuze comprises a cylindrical metal housing 37 having a wall 39 separating a large chamber 41 containing most of the firing train and a smaller chamber 43 containing a booster charge 45, e.g., of tetryl, for exploding the shaped charge 21. Chamber 43 is closed by a cap 47. The rear end of chamber 41 is closed by a metal body member 49 comprising a plate-like portion 51 attached to housing 37, a rearwardly-extending axial plug portion 53 (17 in FIG. I) and a forwardly extending rotor housing portion 55. The plug portion 53 may be sealed in recess 19 of FIG. 1 by means of O-rings 57 mounted in grooves 59 in portion 53.

Wall 39 is formed with a central aperture 61, which may be filled with a tetryl lead 63 for exploding the booster charge 45. The three portions of body member 49 are formed with a continuous axial opening or bore 65 therethrough aligned with aperture 61, as shown best in FIG. 2. The portion 55 of member 49 is further formed with a large-diameter cylindrical recess 67 which axially intersects the longitudinal axis of opening 65 at right angles, is spaced from plate portion 51, and opens forwardly at 69 through the end of portion 55 (FIG. 2). A cylindrical metal arming rotor 71 is mounted within the recess 67 for rotation between an unarmed position, shown in FIG. 2, and an armed position, shown in FIG. 3, as by means of a metal rotor shaft 73, a support plate 75 mounted on portion 55 by screws 77 and a retaining nut 79 (FIG. 3). The rotor 71 is biased toward its armed position by a coil spring 81 connected between the shaft 73 and the portion 55.

The rotor 71 is formed with a central diametral firing train bore 83 containing, in order, an electric detonator 85 having an insulated central terminal pin 87, a cupshaped metal member 89 slidable on pin 87, a coil spring 91, and a cup-shaped slidable metal contact member 93. Members 89 and 93 are insulated from rotor 71 by an insulating guide sleeve 95. A fixed metal contact member 97 is mounted in insulated relation in the opening 65 and adjacent to the rotor recess 67, in position to be contacted by the rotor contact member 93 in the armed position, as shown in FIG. 3, to complete this portion of the electrical circuit for exploding detonator 85. Contact member 97 is connected by a connector 99 to one of four lead-in terminals 32 extending through an insulating plate 101 and the plate portion 51.

In accordance with the present invention, the arming rotor 71 is retained, prior to launch, in the unarmed position of FIG. 2, with the bore 83 out-of-line with the opening 65 and aperture 61, by means of an elongated unitary deformable detent member 103 mounted in the opening 65. In the embodiment shown in FIG. 2, the detent member 103 is made up of a rigid detent portion 105 in the form of a metal strap having one end engaged with a detent shoulder or notch 107 and the other end rigidly attached, as by welding, to the laterally bent closed end 109 of an elongated deformable metal tube 111, the open end of which is rigidly mounted in plug portion 53, as by a ring 113 and peening 115. The tube 111 with its bent end 109 can be fabricated by first closing and partially flattening an end portion of a piece of deformable tubing, such as stain less steel, and then bending at least a part of the flattened end portion away from the central axis, as shown in solid lines in FIG. 2. The strap 105 is preformed to substantially an inverted-S-shape, as shown in FIG. 2, so that it will properly engage the shoulder 107 in unarmed position.

When the propellant 3 is ignited to launch the projectile from the tube 5, the propellant gases enter the open end of tube 111 and the gas pressure causes the flattened end portion 109 to expand and bend (or unbend) to a condition such as that shown in dotted lines in FIG. 2, thus withdrawing the attached detent member 105 from the shoulder 107. This, releases the arming rotor 71, allowing it to be rotated (if not otherwise restrained) by the spring 81 to the armed position of FIG. 3, thereby aligning the detonator 85 with the lead 63 and closing the switch S formed by contacts 93 and 97. Another switch 8:, which is part of the electrical firing circuit, is formed by two spring contacts 1 17 (FIGS. 3 and 5) which, in the unarmed position of the rotor 71 (FIG. 2), are in contact with a metal connector 119 mounted on an insulator 121 embedded in one side of the rotor 71. The fuze 11 also includes a box-like insulating housing 123 having an open end abutting the insulating plate 101 and a side leg 125 in which contact 97 is mounted. Mounted within housing 123 are a capacitance element or condenser 127, a resistor 129, and a blocking detector 131.

The electrical circuit of the fuze is shown in unarmed condition in FIG. 8. The wires 33 and 35 are connected, through two of the terminals 99, the closed switch S and the detector 131, to opposite sides of the condenser 127, for charging the condenser prior to launch. Condenser 127 is also connected, through the detonator 85, the switch S and the other two terminals 99, to the nose cones 9 and 25, which form a third switch S The contacts 117 and 119 of switch S are closed during assembly of the fuze when the rotor 71 is inserted, in its unarmed position, into the recess 67.

In the operation of the fuze 11, the projectile 11 and its propellant 3 are placed in the launch positions in tube 5, with the wires 33 and 35 extending through the tube. The wires 33 and 35 are connected to a battery 133 which charges the condenser 127 through the closed switch S and the detector 131. When the pro pellant 3 is ignited to launch the projectile 1, the resulting gas pressure actuates the detent member 103 to release the arming rotor 71, as described above. If desired, or required by safety regulations, the fuze 11 may also be provided with an independent mechanical rotor restraining means, actuated at or during launch by setback or centrifugal force. After release, the rotor 71 rotates to the armed position of FIG. 3, thus closing switch S opening switch S and aligning the detonator with the explosive charges. During launch, the wires 33 and 35 are separated, as indicated by the Xmarks in FIG. 6. The function of the detector 131 is to prevent premature discharge of the condenser by contact between the loose ends of the wires after separation. On impact of the projectile with a target, the nose cones 9 and 25 collapse, thus closing the switch S and discharging the condenser 127 into the detonator 85, re sulting in successive explosion of the detonator 85, lead 63, booster charge 45 and main charge 21. The function of the resistor 129 is to bleed or discharge the condenser 127 prior to arming of switch S in the event that the nose cones are crushed prior to launch.

The detent member 103 shown in FIGS. 2 and 3 is a unitary member even though it is made of two separate parts welded together, because the welded parts are essentially integral. An alternative embodiment is shown in FIGS. 7 and 8 in which the detent member 103 consists of a strap portion an intermediate closed and sealed, deformable, bent tubular portion 109'; and an open tubular base portion 111', formed from a single piece of elongated deformable metal tubing by flattening and bending operations. The bent tubular portion 109' is readily deformed by the gas pressure during launch. However, the strap portion 105' is relatively rigid with respect to the force exerted thereon by the rotor spring 81 and rotor 71.

I wish it to be understood that I do not desire to be limited to the exact method and detail of construction described for obvious modifications will occur to persons skilled in the art.

Having thus fully described the invention, what is claimed as new and desired to be secured by Letters Patent of the United States is:

l. A fuze for an explosive projectile comprising:

a hollow body;

a firing member mounted in said body for movement between unarmed and armed positions;

means normally biasing said firing member toward said armed position; and

means for retaining said firing member in said unarmed position prior to the launching of said projectile and for releasing said firing member during launch, comprising:

a detent shoulder on said firing member; and

an elongated unitary deformable detent member comprising a first end rigidly mounted in said body, a second end engaging said detent shoulder prior to launch, and fluid pressure means for laterally bending said detent member and withdrawing said second end from said detent shoulder; said detent member comprising a deformable tubular portion, having an open end rigidly mounted in said body and communicating with the exterior thereof and a flattened closed end extending at an acute angle to said open end, and a detent portion having one end essentially integral with said closed end and its other end engaging said detent shoulder; whereby, upon launch, the gas pressure of the propellant causes said closed end to expand and bend toward said axis, thereby withdrawing said detent portion from said detent shoulder.

2. A fuze as in claim 1, wherein said tubular portion and said detent portion are separate members rigidly attached to each other.

3. A fuze as in claim 1, wherein said detent portion is an integral extension of said tubular portion.

4. A fuze as in claim 1, wherein said body has a first bore extending therethrough and a recess normal to and intersecting said bore, and said firing member is an arming member having a second bore therein and is mounted in said recess for movement between an armed position wherein said two bores are aligned and an unarmed position wherein the bores are misaligned.

5. A fuze as in claim 4, wherein said recess is cylindrical in shape, and said arming member is a cylindrical rotor rotatably mounted in said recess.

6. A fuze as in claim 5, wherein said first bore contains an insulated electrical contact positioned adjacent to said recess, and said second bore contains an electric detonator and means for connecting said detonator to said contact when said bores are aligned. 7. An explosive projectile comprising: A. a hollow projectile body having a reduceddiameter recess in the base thereof; B. an explosive charge in said body; C. a fuze mounted in said recess adjacent to said charge, said fuze comprising:

1. a hollow fuze body;

2. a firing member mounted in said fuze body for movement between unarmed and armed positions and comprising an electric detonator and a first switch contact connected thereto;

3. means normally biasing said firing member toward said armed position; and

4. means for retaining said firing member in said unarmed position prior to the launching of said projectile and for releasing said firing member during launch, comprising:

a. a detent shoulder on said firing member; and b. an elongated unitary deformable detent member comprising a first end rigidly mounted in said fuze body, a second end engaging said detent shoulder prior to launch, and fluid pressure means for laterally bending said detent member and withdrawing said second end from said detent shoulder; said detent member comprising a deformable tubular portion, having an open end rigidly mounted in said fuze body and communicating with the exterior thereof and a flattened closed end extending at an acute angle to said open end, and a detent portion having one end essentially integral with said closed end and its other end engaging said detent shoulder; whereby, upon launch, the gas pressure of the propellant causes said closed end to expand and bend toward said axis, thereby withdrawing said detent portion from said detent shoulder; and D. electrical circuit means, including a second switch contact connected to said first contact when said firing member is in its armed position, for initiating the explosion of said detonator. 8. An explosive projectile as in claim 7, wherein said electrical circuit means further includes a condenser, which is charged prior to launch, and a switch which is closed at impact with a target. 

1. A fuze for an explosive projectile comprising: a hollow body; a firing member mounted in said body for movement between unarmed and armed positions; means normally biasing said firing member toward said armed position; and means for retaining said firing member in said unarmed position prior to the launching of said projectile and for releasing said firing member during launch, comprising: a detent shoulder on said firing member; and an elongated unitary deformable detent member comprising a first end rigidly mounted in said body, a second end engaging said detent shoulder prior to launch, and fluid pressure means for laterally bending said detent member and withdrawing said second end from said detent shoulder; said detent member comprising a deformable tubular portion, having an open end rigidly mounted in said body and communicating with the exterior thereof and a flattened closed end extending at an acute angle to said open end, and a detent portion having one end essentially integral with said closed end and its other end engaging said detent shoulder; whereby, upon launch, the gas pressure of the propellant causes saiD closed end to expand and bend toward said axis, thereby withdrawing said detent portion from said detent shoulder.
 2. A fuze as in claim 1, wherein said tubular portion and said detent portion are separate members rigidly attached to each other.
 2. a firing member mounted in said fuze body for movement between unarmed and armed positions and comprising an electric detonator and a first switch contact connected thereto;
 3. means normally biasing said firing member toward said armed position; and
 3. A fuze as in claim 1, wherein said detent portion is an integral extension of said tubular portion.
 4. A fuze as in claim 1, wherein said body has a first bore extending therethrough and a recess normal to and intersecting said bore, and said firing member is an arming member having a second bore therein and is mounted in said recess for movement between an armed position wherein said two bores are aligned and an unarmed position wherein the bores are misaligned.
 4. means for retaining said firing member in said unarmed position prior to the launching of said projectile and for releasing said firing member during launch, comprising: a. a detent shoulder on said firing member; and b. an elongated unitary deformable detent member comprising a first end rigidly mounted in said fuze body, a second end engaging said detent shoulder prior to launch, and fluid pressure means for laterally bending said detent member and withdrawing said second end from said detent shoulder; said detent member comprising a deformable tubular portion, having an open end rigidly mounted in said fuze body and communicating with the exterior thereof and a flattened closed end extending at an acute angle to said open end, and a detent portion having one end essentially integral with said closed end and its other end engaging said detent shoulder; whereby, upon launch, the gas pressure of the propellant causes said closed end to expand and bend toward said axis, thereby withdrawing said detent portion from said detent shoulder; and D. electrical circuit means, including a second switch contact connected to said first contact when said firing member is in its armed position, for initiating the explosion of said detonator.
 5. A fuze as in claim 4, wherein said recess is cylindrical in shape, and said arming member is a cylindrical rotor rotatably mounted in said recess.
 6. A fuze as in claim 5, wherein said first bore contains an insulated electrical contact positioned adjacent to said recess, and said second bore contains an electric detonator and means for connecting said detonator to said contact when said bores are aligned.
 7. An explosive projectile comprising: A. a hollow projectile body having a reduced-diameter recess in the base thereof; B. an explosive charge in said body; C. a fuze mounted in said recess adjacent to said charge, said fuze comprising:
 8. An explosive projectile as in claim 7, wherein said electrical circuit means further includes a condenser, which is charged prior to launch, and a switch which is closed at impact with a target. 